Leucothoe rudicula, White & Thomas, 2009

White, Kristine N. & Thomas, James Darwin, 2009, Leucothoidae *, Zootaxa 2260 (1), pp. 494-555 : 528-531

Leucothoe rudicula sp. nov.

( Figs 21 , 22 )

Type material. Holotype, male, 2.6 mm, AM P 79801; North Point , Lizard Island (14°38’S 145°27’E), rubble sample from vertical cliffs and unconsolidated bottom rubble, 12.2 m, J. D. Thomas, 28 January 1989 ( JDT / LIZ 13 ) . Paratype, male, 2.3 mm, AM P 79802, same station data . Paratype, female, 1.80 mm, AM P 79803, same station data .

Additional material examined. 2 females, 1 male, AM P 79804 ( JDT / LIZ 13 ) .

Type locality. North Point , Lizard Island, Queensland, Australia (14°38’S 145°27’E) .

Etymology. After the Latin ‘ rudicula ’, meaning ‘wooden spoon, spatula’ and referring to the spoon-like apex of the gnathopod 2 carpus.

Description. Based on holotype, male, 2.6 mm, AM P79801.

Head. Head length less than pereonite 1+2, anterior margin truncate, without serrations or teeth, anterodistal margin quadrate with cusp, ventral cephalic keel oblique, rostrum small to medium; eyes with 10 or more ocelli, round. Antenna 1 0.4 x body length; flagellum 7-articulate, peduncle width less than 2 x article 2. Antenna 2 0.3 x body length 0.3, shorter than antenna 1; flagellum 3-articulate. Mandibles lacking molars, palp 3-articulate, ratio of articles 1–3, 1.0:2.6:1.4, article 2 with 4 distal setae, article 3 with 2 distal setae, incisors strongly dentate; left mandible lacinia mobilis moderate in size, strongly toothed, with 8 accessory setae; right mandible lacinia mobilis small, with 8 accessory setae. Upper lip asymmetrically lobate, anterior margin weakly setose. Lower lip inner lobes fused, bare; outer lobes with moderate gape, anterior margins weakly setose. Maxilla 1 palp 2-articulate with 4 distal setae; outer plate with 5 distal spines and 1 distal seta. Maxilla 2 inner plate with 4 distal setae; outer plate with 3 robust and 10 – 12 thin distal setae. Maxilliped inner plates fused, distal margin with v-shaped indentation, with short spines and setae; outer plate smooth, reduced, reaching much less than half of palp article 1, with 4 distal setae and 1 distal spine; palp 4-articulate, article 4 widened proximally, slightly recurved.

Pereon. Coxae 1–4 relative widths 1.0:1.7:1.5:1.8. Gnathopod 1 coxa smooth, anterodistal corner produced, with 1 seta, broadly rounded, distal margin rounded, posterodistal margin rounded, facial setae absent; basis expanded distally, anterior margin with 2 short setae, posterior margin bare; ischium bare; carpus and propodus distally inflated, bulbous; carpus length 5.8 x width, proximal margin weakly serrate, distal margin setose; propodus straight, palm smooth with 18 – 20 distal setae; dactylus smooth, reaching 0.1 x propodus length. Gnathopod 2 coxa length and width subequal, slightly wider than coxa 3, smooth, bare, anterodistally rounded, distal margin evenly rounded, posterior margin rounded, facial setae absent; basis anterodistal margin expanded, with 2 small tubercles, anterior margin with 2 setae, posterior margin bare; ischium with 4 posterodistal setae; carpus 0.4 x propodus length, recurved, distally truncate, spoon-like, anterior margin smooth; propodus posterior margin without teeth/serrations, with 2 mediofacial setal rows, primary mediofacial setal row above midline, reaching 0.8 x propodus length, secondary mediofacial setal row with 2 setae, 1 row of 3 submarginal setae, palm convex with 3 major projections; dactylus recurved, proximal margin smooth, tapered, anterior margin distally subacute, reaching 0.8 x propodus length. Pereopod 3 coxa length 0.8 x width, anterodistal corner over-riding distal face of coxa 2 and extending below it, smooth, bare, anterior margin evenly rounded, distal margin straight, posterior margin straight, facial setae absent. Pereopod 4 coxa smooth, bare, anterior margin subquadrate, distal margin produced, posterior margin weakly excavate, facial setae absent. Pereopods 5–7 coxa facial setae absent; basis width length ratios 1:1.3, 1:1.0, 1:1.0, posterior margins smooth, bare.

Pleon. Epimeron 1 with 2 ventral setae. Epimeron 2 with 3 ventral setae. Epimeron 3 bare, posteroventral margin subquadrate. Uropod 3 missing. Uropods 1–2 relative lengths 1.0:0.7; peduncle 0.7 x inner ramus length. Uropod 1 outer ramus 0.7 x inner ramus length; inner and outer ramus with robust setae. Uropod 2 outer ramus 0.8 x inner ramus length; inner and outer ramus with a single robust seta. Telson 2.5 x longer than wide, apex tridentate.

Female (sexually dimorphic characters). Based on paratype, female, 1.8 mm, AM P 79803. Gnathopod 1 carpus distal margin with 3 setae; basis anterior margin bare, posterior margin with 2 short setae. Gnathopod 2 propodus mediofacial setal row with fewer setae. Pereopods 5–6 coxa each with 2 proximal facial setae .

Habitat. Coral rubble from vertical cliffs and unconsolidated bottom rubble.

Remarks. Leucothoe rudicula sp. nov. appears to be very closely related to L. lihue based on the stout gnathopod 1 propodus, short gnathopod 1 dactylus length and the distinct convex gnathopod 2 propodus with 3 strong palmar projections. Leucothoe lihue differs from L. rudicula in its dense covering of setae on the maxilliped inner plates. Leucothoe rudicula shares its truncate, spoon-like gnathopod 2 carpus with L. alata , L. lihue , L. spinulosa , L. tridens and Leucothoe epidemos sp. nov. and its strongly recurved gnathopod 2 dactylus with L. pollexa sp. nov. Leucothoe rudicula shares its general gnathopod 1 shape with species in the genus Paraleucothoe ; however, its propodus is much narrower than in Paraleucothoe . The strong dentition of the propodus palm of gnathopod 2 is shared with L. ashleyae , L. hornelli , L. stegoceras , L. adelphe sp. nov. and L. serrata sp. nov. but differs in most other respects, namely the short dactylus of gnathopod 1.

Distribution. Australia. Queensland: Lizard Island (current study).

Figures

FIGURE 21. Leucothoe rudicula sp. nov., holotype, male, 2.6 mm, AM P79801 (JDT/LIZ 13), North Point, Lizard Island, Great Barrier Reef.

FIGURE 22. Leucothoe rudicula sp. nov., holotype, male, 2.6 mm, AM P79801 (JDT/LIZ 13), North Point, Lizard Island, Great Barrier Reef.